The US has snubbed Chinese proposals to ease the Korean confrontation through emergency multiparty talks including the North, with a White House spokesman dismissing the suggestion as a "PR activity".

Beijing had called for the talks by the six parties involved in the stalled North Korean aid-for-denuclearisation discussions after a Northern artillery barrage killed four people, including two civilians, on a Southern island of Yeonpyeong. Tensions on the peninsula are at their highest for years, with joint military drills by the US and the South under way in the Yellow Sea today.

The White House spokesman, Robert Gibbs, told reporters: "The United States and a host of others, I don't think, are not interested in stabilising the region through a series of PR activities."

According to the New York Times, he added that talks "without an understanding and agreement from the North Koreans to both end their behaviour as they exhibited last week, but also to come to the table with a seriousness of purpose on the denuclearisation issue – without that seriousness of purpose, they're just a PR activity".

Seoul has indicated its lack of interest, and Japan's foreign minister, Seiji Maehara, said last night that such talks were "impossible" after the Yeonpyeong shelling.

South Korea said today its officials would meet counterparts from Japan and the US in Washington early next month to discuss the North's expanded nuclear programme, the attack on Yeonpyeong and a Chinese proposal for emergency talks.

China repeated its call for dialogue, with the foreign ministry spokesman, Hong Lei, telling a regular press briefing: "Bringing the issue back to dialogue and consultation at an early date is in the common interest of all parties and is the common aspiration of the international community. Ensuring the peace and stability of the Korean peninsula is the shared responsibility of all sides."

Hong said China had made the proposal "to ease the situation" and to provide a platform for dialogue.

Beijing has come under intense pressure to rein in its neighbour and ally over the attack, near the disputed maritime border of the two Koreas. It has refrained from criticising Pyongyang – which says it acted in response to the South's live-fire exercise – instead urging both sides to show restraint.

US diplomatic cables revealed today by the Guardian and other WikiLeaks partners show China's frustration with the North. According to the documents, a south Korean official "claimed [high-level Chinese officials] believed Korea should be unified under ROK [South Korean] control". Another told the US Pyongyang was acting like a "spoiled child" to get Washington's attention.

China does not want instability and a flood of refugees, and analysts believe it would be deeply unhappy to see a US-dominated Korea on its doorstep.

The government has been heavily criticised at home, with some commentators saying it mishandled the initial response to the artillery bombardment. The defence minister resigned last week.

According to a spokeswoman for his office, Lee told his colleagues: "We should recognise that (South Korea) is confronting the world's most belligerent group."

He added that there seemed to be a perception that dealing with a national crisis was a task only for the defence ministry, when it should be a matter for all of them.

The high stakes in the confrontation were underscored when North Korea detailed its increased nuclear programme for the first time today, saying it had thousands of centrifuges. It added that these were for peaceful purposes. It announced the expansion in an article in the Rodong Sinmun newspaper, carried by state news agency KCNA.